Lionel Lapierre

Robust Nonlinear Path-Following Control of an AUV

This paper develops a robust nonlinear controller that asymptotically drives the dynamic model of an autonomous underwater vehicle (AUV) onto a predefined path at a constant forward speed. A kinematic controller is first derived, and extended to cope with vehicle dynamics by resorting to backstepping and Lyapunov-based techniques. Robustness to vehicle parameter uncertainty is addressed by incorporating a hybrid parameter adaptation scheme. The resulting nonlinear adaptive control system is formally shown and it yields asymptotic convergence of the vehicle to the path. Simulations illustrate the performance of the derived controller .

Smooth transition of AUV motion control: From fully-actuated to under-actuated configuration

This paper addresses the problem of steering autonomous underwater vehicle (AUV) along a desired horizontal path throughout the full-range low-speed and high-speed profiles, experiencing both fully-actuated and under-actuated configurations. First, a nonlinear controller adopting Lyapunov’s direct method and backstepping technique is proposed for under-actuated AUV, based on the Line-of-Sight guidance built in a moving Frenet–Serret frame. And then, the controller is adapted to fully-actuated AUV except that the control computation for the evolution of the side-slip angle is different from the case of under-actuated one. Hence, both the fully-actuated and under-actuated configurations are under the same control framework, which enables a smooth continuous transition between two configurations in a synthesized controller. Finally, simulation results illustrate the performance of the proposed control design, where the varied control efforts in the sway direction clearly show the transitions from fully-actuated to under-actuated configuration.

Distributed Control of Coordinated Path Tracking for Networked Nonholonomic Mobile Vehicles

This paper addresses the problem of coordinated path tracking for networked nonholonomic mobile vehicles, while building and keeping a desired formation. The control laws proposed are categorized into two envelopes by integrating individual path tracking and global virtual structure approaches. One is steering individual vehicles to track virtual vehicles moving along predefined paths, generated by a formation reference vehicle (FRV) of a time-varying desired virtual structure. The other is ensuring paths to be well tracked in order to build a geometric formation, through the distributed feedback law for path parameters related to the virtual vehicles, such that the physical vehicles are on the desired placements of the formation structure. Within this framework, geometric path tracking is achieved via nonlinear control theory, where an approaching angle is injected as a heading guidance design. The distributed feedback law is analyzed under communication constraints using algebraic graph theory. It is formally shown that the path tracking error of each vehicle is reduced to zero, and vehicles in the networked team globally asymptotically converge to a desired formation with equal path parameters. Simulation results illustrate the effectiveness of the proposed control design.

Synchronized path following control of multiple homogenous underactuated AUVs

This paper addresses the problem of synchronized path following of multiple homogenous underactuated autonomous underwater vehicles (AUVs). The dedicated control laws are categorized into two envelopes: One is steering individual underwater vehicle to track along predefined path, and the other is ensuring tracked paths of multiple vehicles to be synchronized, by means of decentralized speed adaption under the constraints of multi-vehicle communication topology. With these two tasks formulation, geometric path following is built on Lyapunov theory and backstepping techniques, while injecting helmsman behavior into classic individual path following control. Synchronization of path parameters are reached by using a mixture of tools from linear algebra, graph theory and nonlinear control theory. A simple but effective control design on direct inter-vehicle speed adaption with minimized communication variables, enables the multi-AUV systems to be synchronized and stabilized into an invariant manifold, and all speeds converge to desired assignments as a byproduct. Simulation results illustrate the performance of the synchronized path following control laws proposed.

Guidance of Unmanned Surface Vehicles: Experiments in Vehicle Following

Virtual target-based path-following techniques are extended to execute the task of vehicle following in the case of unmanned surface vehicles (USVs). Indeed, vehicle following is reduced to the problem of tracking a virtual target moving at a desired range from a master vessel, while separating the spatial and temporal constraints, giving priority to the former one. The proposed approach is validated experimentally in a harbor area with the help of the prototype USVs ALANIS and Charlie, developed by Consiglio Nazionale delle Ricerche-Istituto di Studi sui Sistemi Intelligenti per lAutomazione (CNR-ISSIA).

PATH-FOLLOWING ALGORITHMS AND EXPERIMENTS FOR AN AUTONOMOUS SURFACE VEHICLE

Abstract This paper addresses the problem of path-following in two-dimensional space, for underactuated surface autonomous robots, defining a set of guidance laws either at kinematic and dynamic level. The proposed nonlinear Lyapunov- based control law yields convergence of the path following error coordinates to zero. Furthermore, the introduction of a dynamic for the target to be followed on the path, removes singularity behaviors present in other guidance algorithms proposed in the literature. Dynamic of the vehicle is then taken into account, applying the Backstepping technique. Some heuristic approaches are then proposed to face the problem of speed of advance adaptation based on path curvature measure and steering action prediction. Finally a set of experimental results of all the proposed guidance laws are presented.

Path tracking: Combined path following and trajectory tracking for autonomous underwater vehicles

This paper proposes a novel control strategy for autonomous underwater vehicles (AUVs), named as path tracking, which combines the conventional path following and trajectory tracking control in order to achieve smooth spatial convergence and tight temporal performance as well. This idea is inspired by the previous work of Hindman [1] and Encarnacao [2], however, the path tracking design herein goes from path following to trajectory tracking, which indeed is an inverse way from the previous solutions so that the complex projection algorithm resulting in a local stability is avoided. A kinematics controller is first derived by using Lyapunov direct method where a virtual path parameter is introduced to bring an extra control degree of freedom, and then it is extended to the dynamics of AUVs based on backstepping technique. The resulting nonlinear control design is formally shown and it yields global asymptotic convergence of the AUV to the path. Finally, simulation results illustrate the efficiency of the path tracking control design for AUVs.

Survey on Fuzzy-Logic-Based Guidance and Control of Marine Surface Vehicles and Underwater Vehicles

Fuzzy logic control, due to its simple control structure, easy and cost-effective design, has been successfully employed to the application of guidance and control in robotic fields. This paper aims to review fuzzy-logic-based guidance and control in an important branch of robots—marine robotic vehicles. First, guidance and motion forms including the maneuvering, path following, trajectory tracking, and position stabilization are described. Subsequently, the application of three major classes of fuzzy logic control, including the conventional fuzzy control (Mamdani fuzzy control and Takagi–Sugeno–Kang fuzzy control), adaptive fuzzy control (self-tuning fuzzy control and direct/indirect adaptive fuzzy control), and hybrid fuzzy control (fuzzy PID control, fuzzy sliding mode control, and neuro-fuzzy control) are presented. In particular, we summarize the design and analysis process of direct/indirect adaptive fuzzy control and fuzzy PID control in marine robotic fields. In addition, two comparative results between hybrid fuzzy control and the corresponding single control are provided to illustrate the superiority of hybrid fuzzy control. Finally, trends of the fuzzy future in marine robotic vehicles are concluded based on its state of the art.

A guaranteed obstacle avoidance guidance system

This paper presents a practical solution to the guidance of a unicycle type robot, including path following, obstacle avoidance and the respect of wheeled actuation saturation constraint, without planning procedure. These results are based on an extension of previous results on path following control including actuation saturation constraints. New solution for obstacle avoidance, with guaranteed performance, is proposed.

Coordinated path following control of multiple nonholonomic vehicles

This paper addresses the problem of coordinated path following control of multiple nonholonomic vehicles. The control laws are derived based on the leader-follower strategy, driving unicyle-type nonholonomic vehicles at kinematic level onto predefined parallel paths, while keeping an in-line formation. Due to the spatial-temporal decoupling characteristics of individual path following controller, the velocity of the follower can be adapted only based on the information of generalized along-path length from the leader, which keeps the inter-vehicle communication to a minimum. Simulation results illustrate the efficacy of the solution to coordinated control proposed here. Moreover, the theoretical analysis in this paper reveals some important issues raising that the path following control on the first-order unicyle-type nonholonomic systems can be extended to underactuated AUVs in future work.